Clip unit and ligation device using the same

ABSTRACT

A clip unit for ligating a biological body includes: a clip body having a pair of arm parts; and a fastening ring arranged in an outside of the clip body, and configured to fasten the arm parts, in which: the fastening ring includes a flap part configured to expand diametrically outward from the fastening ring, and a flap retaining unit configured to retaining an expansion extent of the flap part at a given extent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 fromJapanese Patent Application No. 2011-202024 filed on Sep. 15, 2011; theentire content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to a clip unit and a ligation device using thesame.

2. Related Art

In general, a ligation device includes a clip unit located at a frontend of an elongated flexible sheath extending from a handle manipulationunit. The clip unit is driven by reciprocating a manipulation wire,which is inserted through the sheath, in the axial direction of thesheath or by rotating the manipulation wire around the axis of thesheath at the handle manipulation unit. An endoscope operator mayintroduce the clip unit into a body cavity by inserting the sheath ofthe ligation device into a treatment instrument insertion channel formedin an insertion part of the endoscope. This type of ligation device isdescribed, for example in Patent Document 1 (JP-B-4116049) and PatentDocument 2 (JP-B-4472719).

A clip unit 301 is embedded in a sheath 303 as illustrated in FIG. 47Awhen introduced into a body cavity, and the clip unit 301 extends to theoutside and revealed from the front end of the sheath 303 as illustratedin FIG. 47B when arriving at a target affected part. The clip unit 301is provided with flap parts 305, 305 elastically biased diametricallyoutward, so that when the flap parts 305, 305, which have been closedwithin the sheath, protrude from the sheath 303, the flap parts 305, 305are expanded diametrically outward. Once the flap parts 305, 305 areexpanded, when the clip unit 301 is pulled into the sheath 303 side, therear end of the flap parts abuts against the front end of the sheath,thereby being stopped. As a result, the clip unit 301 is positioned inrelation to the sheath 303, in which the position is set as a treatmentstarting position.

SUMMARY OF THE INVENTION

However, both the flap parts 305, 305 of the clip unit 301 illustratedin FIG. 47B are kept expanded diametrically outward by elasticresilience. For that reason, the expansion extent of the flap parts maybe fluctuated due to various variations in manufacturing, such as adifference in quality of material and a dimensional error of the flapparts. Due to the fluctuation of the expansion extent of the flap parts,the flap parts may sometimes abut abnormally against the front end ofthe sheath such that the clip unit 301 is positioned at a slant inrelation to the axis of the sheath.

In addition, the positioning posture of the clip unit 301 may beinfluenced by the variation in the sheath 303 side besides thefluctuation in the flap parts. Since the sheath 303 is repeatedly usedafter replacing the clip unit 301 as well as suffers from variousmanufacturing changes like the flap parts, a dimensional change causedby, for example, abrasion may occur in the sheath 303. Like this, it issometimes impossible to normally set the clip unit 301 to coincide withthe axis of the sheath when the clip unit 301 is positioned in relationto the front end of the sheath 303.

Thus, the object of the present invention is to provide a clip unit thatcan always be precisely positioned in relation to a sheath member toaxially coincide with the sheath member, and a ligation device using thesame, and to enable a smooth and reliable ligation action.

(1) According to an aspect of the invention, a clip unit for ligating abiological body includes: a clip body having a pair of arm parts; and afastening ring arranged in an outside of the clip body, and configuredto fasten the arm parts, in which: the fastening ring includes a flappart configured to expand diametrically outward from the fastening ring,and a flap retaining unit configured to retaining an expansion extent ofthe flap part at a given extent.

(2) According to another aspect of the invention, a ligation deviceincludes: the clip unit of (1); a flexible elongated sheath member; atransmission member inserted into the sheath member to be capable ofbeing reciprocated, and configured to transmit driving force to the clipunit connected to the front end of the transmission member; and amanipulation unit arranged on a base end side of the sheath memberopposite to the clip unit, and configured to transmit the driving forceto the transmission member.

With the inventive clip unit, and the ligation device using the same,the clip unit can always be precisely positioned in relation to a sheathmember to axially coincide with the sheath member, and a smooth andreliable ligation action is enabled.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an entire configuration of a ligation device fordescribing an exemplary embodiment of the present invention.

FIG. 2 is illustrates the configuration of a clip unit partially incut-away.

FIG. 3 is an exploded perspective view of the clip unit illustrated inFIG.

FIGS. 4A and 4B are a side view and a front view of the clip body,respectively.

FIG. 5 is a bottom view of the clip body shown in the directionindicated by arrow V1 in FIG. 4B.

FIGS. 6A and 6B are a side view and a front view of the front end sideof an inner fastening ring, respectively, and FIG. 6C is the side viewof the rear end side of the inner fastening ring.

FIG. 7 is a cross-sectional view taken along line A-A in FIG. 6B.

FIG. 8A is a perspective view illustrating a state in which the clipbody and the inner fastening ring are engaged with each other withoutshowing an outer fastening ring, and FIG. 8B is a cross-sectional viewtaken along line B-B in FIG. 8A.

FIGS. 9A and 9B are a side view of the front end side of the outerfastening ring, and a front view thereof, respectively.

FIG. 10 is a cross-sectional view taken along line C-C in FIG. 9A.

FIG. 11 is a cross-sectional view illustrating the outer fastening ringand the inner fastening ring in the state where they are engaged witheach other.

FIG. 12 is a cross-sectional view of the handle manipulation unit of theligation device.

FIG. 13 is an enlarged cross-sectional view of the front end part of themanipulation unit body and an area in the vicinity of the front end partof the slitting section illustrated in FIG. 12.

FIG. 14 is an exploded perspective view of a manipulation wire anchorfor anchoring the manipulation wire to a slider.

FIG. 15 is a sectioned perspective view of the slider body.

FIG. 16 is a cross-sectional view of a front end sheath.

FIG. 17 is a front view of the hook and the guide bead which are fixedto the front end of the manipulation wire.

FIG. 18 is a cross-sectional view taken along line D-D in FIG. 17.

FIG. 19 is a perspective view illustrating, partially in cut-away, theclip body and the hook in the state where they are engaged with eachother.

FIG. 20 is a perspective view of a clip case.

FIG. 21 is an exploded perspective view of the clip case.

FIG. 22 is a side view of the clip case.

FIGS. 23A to 23D are explanatory views illustrating a sequence ofmounting the clip unit of the clip case to the hook.

FIG. 24 is an enlarged view of the part indicated by arrow A3 in thebottom case of FIG. 23A.

FIG. 25 is a perspective view of the part indicated by arrow A3 in thebottom case of FIG. 23A.

FIGS. 26A to 26C are explanatory views illustrating the hook from thestate where the hook is inserted into the connection tail section of theclip body to the state where the hook is connected to the connectiontail section in a step-by-step manner.

FIG. 27 is an enlarged explanatory view illustrating the flap parts inthe state of being closed.

FIG. 28A is an explanatory view illustrating a state where the clip bodyand the outer fastening ring are connected with each other, and FIG. 28Bis an explanatory view illustrating the front end sheath curved in theconnected state of FIG. 28A.

FIG. 29 is an explanatory view illustrating a configuration example inwhich the guide bead is replaced by a guide spring.

FIG. 30 is an explanatory view illustrating a configuration example inwhich a guide bead is arranged at the rear end of the guide spring.

FIGS. 31A to 31F are explanatory views illustrating states where the armparts of the clip unit are expanded from the front end sheath.

FIGS. 32A to 32E are explanatory views illustrating the actions of thearm parts of the clip unit, from expanding after having protruded to theoutside from the front end sheath to ligating a biological tissue, in astep-by-step mariner.

FIG. 33A is an explanatory view illustrating the appearance of anexpansion retaining protrusion of the inner fastening ring entering intothe slit part in the base end section, and FIG. 33B is an explanatoryview illustrating the appearance of the expansion retaining protrusionabutting against the front end of the slit part.

FIG. 34 is an explanatory view illustrating a rotation operation of themanipulation unit body in relation to the finger pull ring.

FIG. 35 is an explanatory view illustrating a disengagement preventionprotrusion of an arm part locked by a stepped part formed by aconstricted spot of the outer fastening ring.

FIG. 36 is a view shown in the direction indicated by arrow V2 in FIG.35.

FIG. 37 is an explanatory view illustrating, partially in cut-away, theclip unit in the state where the clip unit has completed the ligation.

FIGS. 38A and 38B are explanatory views illustrating the hook and theconnection tail section in the state where the hook and the connectiontail section are engaged with each other, and in the state where thehook and the connection tail section is started to be disconnected,respectively.

FIGS. 39A to 39C are explanatory views illustrating a process ofreleasing the J-shaped claw parts from the engagement in a step-by-stepmanner.

FIG. 40A is a partial configuration view of a connection tail sectionformed with a pair of engagement claw parts, and FIG. 40B is a bottomview of FIG. 40A.

FIG. 41A is a partial configuration view of a connection tail sectionwith an engagement claw part arranged in an opening formed in an armpart, and FIG. 41B is a bottom view of FIG. 41A.

FIG. 42 is an explanatory view illustrating a construction in which areinforcement rib is provided to extend in the longitudinal direction ofeach of the arm parts with a bending point of the arm part as thecenter.

FIG. 43 is a cross-sectional view taken along line E-E of FIG. 42.

FIG. 44 is a perspective view of an inner fastening ring of anotherexample of configuration.

FIG. 45 is an explanatory view for describing the action of the flapparts illustrated in FIG. 44

FIG. 46 is a perspective view schematically illustrating a constructionin which a flap part is provided in a single fastening ring.

FIGS. 47A and 47B are explanatory views illustrating a conventionalligation device in a state where the clip unit is embedded in thesheath, and in astute where the clip unit is revealed to the outside ofthe sheath.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Now, exemplary embodiments of the present invention will be describedwith reference to drawings.

FIG. 1 is an entire configuration view illustrating a ligation device asa medical treatment instrument for describing an exemplary embodiment ofthe present invention.

A ligation device 100 includes a clip manipulation device 11 which isloaded with a clip unit 13. The clip manipulation device 11 includes afront end sheath 15 configured as an insertion part to be inserted intoa channel of an endoscope (not shown) to be inserted into a body cavity,and a handle manipulation unit 17 located at the base end side of thefront end sheath 15. The front end sheath 15 and the handle manipulationunit 17 are interconnected by a base end sheath 19, and a manipulationwire 21 is inserted through the inside of the front end sheath 15 andthe inside of the base end sheath 19 to be capable of being reciprocatedin the axial direction.

The front end sheath 15 and the base end sheath 19 are configured as aguide tube formed by, for example, a densely wound stainless steel coil.The manipulation wire 21 is formed by a stranded metal wire with aproper elasticity, such as, for example, a stainless steel and a NiTialloy. In addition, to the front end of the manipulation wire 21 whichis opposite to the handle manipulation unit 17, a hook 23 and a guidebead 25 are fixed in this order from the front end.

The clip unit 13 includes a fastening ring 26 formed as a cylindricalbody, and a clip body 27 supported in the fastening ring 26, and thefastening ring 26 is mounted on the hook 23 provided at the front end ofthe manipulation wire 21.

The handle manipulation unit 17 includes: a manipulation unit body 33 towhich the base end side of the base end sheath 19 is fixed to berotatable about the axis thereof; a slider 35 connected to be restrainedfrom being rotated in relation to the manipulation wire 21; and a fingerpull ring 37 provided at the rear end of the manipulation unit body 33to be rotatable. The slider 35 is arranged to be restrained from beingrotated in relation to the manipulation unit body 33 but to be capableof reciprocating in the axial direction of the sheath.

The handle manipulation unit 17 is capable of reciprocating the clipunit 13 connected to the manipulation wire 21 at the front end of thefront end sheath 15 in the axial direction of the sheath by relativelymoving the manipulation unit body 33 and the slider 35 in a longitudinaldirection. In addition, by rotating the manipulation unit body 33 andthe slider 35 around the axis thereof, the clip unit 13 connected to themanipulation wire 21 is allowed to be rotated about the sheath axis.

That is, the clip manipulation device 11 is configured such that, whenthe slider 35 is moved away from the finger pull ring 37, themanipulation wire 21 is moved in the direction for making themanipulation wire 21 protrude forward from the front end sheath 15, andto the contrary, when the slider 35 is moved toward the finger pull ring37, the manipulation wire 21 is moved in the direction for making themanipulation wire 21 be pulled into the front end sheath 15. Inaddition, when the manipulation unit body 33 and the slider 35 arerotated around the axis, the manipulation wire 21 is rotated togetherwith the slider 35. The clip unit 13 loaded in the front end side of themanipulation wire 21 is maintained in the state in which it isrestrained from being rotated by the hook 23, which will be describedlater. Accordingly, the clip unit 13 is released by the extension of themanipulation wire 21, and rotationally driven by the rotation of themanipulation wire 21.

The manipulation wire 21 is capable of using an appropriate wire whichmay readily transmit the rotation of one end thereof to the other end.For example, even a torque wire may be used which is difficult toproduce rollover. In addition, a cable obtained by wire-drawing astainless steel may be also used.

In the following description, a direction directed toward the fingerpull ring 37 of the handle manipulation unit 17 of the ligation device100 is referred to as a base end direction or rear side, and a directiondirected toward the front end of the clip body 27 is referred to as adistal end direction or front side. In addition, the axial direction ofthe fastening ring 26 of the clip unit 13, as well as the axialdirection of the front end sheath 15, the base end sheath 19, and themanipulation wire 21 will be referred to as a longitudinal axisdirection.

<Clip Unit>

Next, the configuration of the clip unit 13 will be described in detail.

FIG. 2 is a configuration view illustrating, partially in cut-way, theclip unit, and FIG. 3 is an exploded perspective view of the clip unit.The clip unit 13 includes a fastening ring 26 and a clip body 27. Thefastening ring 26 is constituted with an outer fastening ring 29 formedas a cylindrical body, and an inner fastening ring 31 inserted into theinside of the cylindrical body of the outer fastening ring 29.

The clip body 27 includes: a pair of arm parts 39, 39 which are expandedand biased in relation to each other; abuse end section 41 formed in aloop shape for interconnecting the base ends of the arm parts 39, 39; aconnection tail section 43 formed on the base end section 41 at the sideopposite to the pair of arm parts 39, 39 (at the rear side). The armparts 39, 39 may be closed to each other when inserted into thefastening ring 26, so that a biological tissue can be grasped by the armparts 39, 39.

All the clip body 27, the outer fastening ring 29, and the innerfastening ring 31 may be formed from a metallic material, such as astainless steel. The clip body 27 is formed by bending a band-shapedresilient metallic plate material in a U-shape. The outer fastening ring29 is a cylindrical member and accommodates the inner fastening ring 31within the inside thereof. The inner fastening ring 31 includes a pairof flap parts 45, 45 which are configured to be expanded and biaseddiametrically outward by elastic resilience.

The outer fastening ring 29 is formed with a pair of flap protrudingholes 93, 93 at positions corresponding to the flap parts 45, 45 of theinner fastening ring 31, so that when the inner fastening ring 31 isaccommodated in the outer fastening ring 29, the flap parts 45, 45partially protrude radially outward from the flap protruding holes 93,93.

The clip unit 13 is formed by inserting the base end section 41 and theconnection tail section 43 of the clip body 27 into the outer fasteningring 29, which accommodates the inner fastening ring 31, from the frontside of the outer fastening ring 29. A hook 23 is engaged with the clipunit 13, in which the hook 23 is provided at the front end of themanipulation wire 21 and inserted into the clip unit 13 from the rearside of the clip unit 13.

<Clip Body>

FIGS. 4A and 4B are a side view and a front view of the clip body,respectively, and FIG. 5 is a bottom view of the clip body viewed in thedirection indicated by arrow V1 in FIG. 4B.

The clip body 27 is formed by bending a band-shaped metallic platematerial in such a mariner that a pair of the arm parts 39, 39, the baseend section 41 and the connection tail section 43 are integrally formed.The base end section 41 and the connection tail section 43 extend fromthe connection base section 40 which has a flat surface which isperpendicular to the longitudinal central axis of the clip body 27. Apair of loop parts 47, 47 extend from the connection base section 40 andabut against each other at the arm part 39 side of the loop parts 47, 47(loop ends), whereby the base end section 41 is formed in a loop shapein the entirety. The loop parts 47, 47 are arranged symmetrically, andconnected to the arm parts 39, 39, respectively, in the side opposite tothe connection base section 40.

At the abutting loop ends, one of the loop parts 47, 47 is formed withan engagement hole 49, and the other of the loop parts 47, 47 is formedwith a deviation prevention claw 51 for engaging with the engagementhole 49. As the engagement hole 49 and the deviation prevention claw 51are engaged with each other, the pair of arm parts 39, 39 are preventedfrom being deviated in the longitudinal axis direction and in thedirection perpendicular to the longitudinal axis direction. In addition,each of the loop parts 47, 47 is formed with a slit part 53 along theloop.

The arm parts 39, 39, which are provided to extend further beyond theloop end of the loop parts 47, 47, are formed by band-shaped resilientmetallic plate material members which are symmetrically arranged to beopposed to each other. The arm parts 39, 39 include: linear plate parts57 with a predetermined width in the direction perpendicular to theexpanding direction of the arm parts 39, 39; disengagement preventionprotrusions 59 which are wider than the linear plate parts 57; middleparts 63, each of which is formed with a pull-in prevention protrusion61 via a taper part 65; and front end parts 67 configured to be capableof grasping a biological tissue therebetween, in this order from thebase end section 41. The arm parts 39, 39 are biased to be expanded fromeach other with reference to the engagement hole 49 and the deviationprevention claw 51 by the elastic resilience of the clip body 27.

A pair of the arm parts 39, 39 are formed in circular arc shapes with acurvature in such a manner that the linear plate parts 57 are bulginginwardly each other. At the front end sides of the linear plate parts57, first bending points 64 a are provided where the arm parts 39, 39are bent outward, and in the vicinity of the pull-in preventionprotrusions 61 of the middle parts 63, second bending points 64 b areprovided where the arm parts 39, 39 are bent inwardly. In addition, thearm parts 39, 39 are inwardly bent at third bending points 64 cpositioned closer to the front end side than the middle parts 63,thereby forming the front end parts 67.

When a pair of the arm parts 39 are opened by the elastic resilience ofthe clip body 27, the pair of front end parts 67, 67 are largely spacedfrom each other, thereby forming a grasping gap 69 between the front endparts 67, 67. When the arm parts 39 are closed, the front end parts 67,67 approach each other to be capable of grasping a biological tissue. Inaddition, as illustrated in FIG. 4, each of the front ends of the frontend parts 67, 67 may be formed to have an obtuse-angled convex part andan obtuse-angled concave part to be engaged with each other, or may havea linear shape.

The connection tail section 43 includes: a pair of plate-shaped arms 71extending from the connection base section 40 of the base end section 41in the direction opposite to the pair of arm parts 39; and J-shaped clawparts 73 as engagement claw parts, which are U-turned at the rear ends71 a of the arms 71, respectively, and extend from the rear ends 71 a ofthe arms 71 toward the front side (in the direction to the arm parts39). The pair of arms 71 define a space for accommodating the hook 23.Each of the J-shaped claw parts 73 is inclined inwardly at the front end73 a in advance, in which the J-shaped claw parts 73 are inclined moreinwardly than the arms 71. In addition, each of the arms 71 extendingfrom the connection base section 40 with a predetermined width has awider part at the central area thereof, and engagement step parts 75 areformed by the wider parts.

As illustrated in FIG. 5, the connection tail section 43 is formed insuch a manner that an arm part center line ACL and a connection tailsection center line JCL are different in phase by an angle θ (forexample, 40 degrees to 70 degrees, preferably 55 degrees to 60 degrees),wherein the arm part center line ACL extends through the center of thepair of arm parts 39 which are provided to extend from the base endsection 41, and the connection tail section center line JCL extendsthrough the center of a pair of arms 71 of the connection tail section43 which are provided to extend from the connection base section 40 ofthe base end section 41. That is, the expansion direction of the armparts 39 are determined to intersect the expansion direction of theconnection tail section 43 with the angle θ.

In addition, the loop parts 47, 47 of the base end section 41 areconnected to the side surfaces of the flat part of the connection basesection 40 via constricted spots 50 illustrated in FIG. 5 (see FIG. 8B),respectively. As a pair of the loop parts 47, 47 are connected to theconnection base section 40 via the constricted spots 50, external forcesapplied to the arm parts 39, 39 are retrieved at the constricted spots50, and deformation is prevented from reaching the connection basesection 40 and the connection tail section 43. The constricted spots 50also prevent external forces from reaching the arm parts 39, 39 from theconnection tail section 43.

<Inner Fastening Ring>

FIGS. 6A and 6B are a side view and a front view of the front end sideof the inner fastening ring, respectively, and FIG. 6C is a side view ofthe rear end side of the inner fastening ring. FIG. 7 illustrates across-sectional view taken along line A-A in FIG. 6B.

The inner fastening ring 31 includes a ring part 77, and a pair of flapparts 45, 45 cantilevered on the ring part 77, more specificallyextending from a one side end face 77 a. The pair of flap parts 45, 45are formed by slightly expanding free ends 45 a from the axial directionat two diametrically outer edge positions on the one side end face 77 aof the ring part 77.

On the one side end face 77 a to which the flap parts 45, 45 areconnected, a pair of recesses 81, 81 are formed, and the engagement stepparts 75 of the clip body 27 (see FIG. 4) are engaged in the recesses8), 81, respectively. In addition, on the front end face 77 b of thering part 77 opposite to the one side end face 77 a, an expansionretaining protrusion 55 is formed to protrude from the ring part 77 toan inclined front side facing diametrically inward. The expansionretaining protrusion 55 will be described later.

Each of the flap parts 45, 45 is formed to have a circular arc shape ina diametrical cross-section perpendicular to the axial direction, and isformed with a bulge part 83 opposite to the other flap part 45 at theaxially central area thereof, in which the length of the circular arc inthe diametrical cross-section is increased at the bulge part 83. Thebulge parts 83 are formed with flap locking holes 85, 85, respectively.The inner fastening ring 31 is formed in such a manner that when theflap parts 45 are closed, the outer diameter of the inner fastening ring31 is substantially equal to or slightly smaller than the inner diameterof the outer fastening ring 29.

The inner fastening ring 31 and the clip body 27 are engaged with eachother as follows. FIG. 8A is a state in which the clip body 27 and theinner fastening ring 31 are engaged with each other without showing anouter fastening ring 29, and FIG. 8B is a cross-sectional view takenalong line B-B in FIG. 8A. As shown in FIG. 8A, the connection tailsection 43 of the clip body 27 is inserted into the ring part 77 of theinner fastening ring 31 in the P1 direction in FIG. 8A. At this time, asillustrated in FIG. 5B, the engagement step parts 75 of the connectiontail section 43 are snugly fitted in the recesses 81 provided in the oneside end face 77 a of the ring part 77, such that the engagement stepparts 75 and the recesses 81 are engaged with each other. Accordingly,even when an attempt is made to pull out the clip body 27 from the innerfastening ring 31 in the P2 direction in FIG. 8A, the engagement stepparts 75 and the recesses 81 abut against each other such that theycannot be separated from each other.

<Outer Fastening Ring>

FIGS. 9A and 9B are a side view at the front end side and a front viewof the outer fastening ring, respectively, and FIG. 10 is across-sectional view taken along line C-C in FIG. 9A.

The outer fastening ring 29 includes a cylindrical section 87, aconstricted spot 89 formed by reducing the diameter of the cylindricalsection 87 in the vicinity of the front end of the cylindrical section87, and a taper section 91 extending from the constricted spot 89 insuch a manner that the diameter of the taper section 91 is graduallyincreased as approaching the front end side. The inner diameter of thecylindrical section 87 is slightly larger than the outer diameter of thering part 77 of the inner fastening ring 31 (see FIG. 6), such that theinner fastening ring 31 is capable of being fitted in the inside of theouter fastening ring 29. In addition, in the cylindrical section 87, apair of flap protruding holes 93 are formed to be elongated along theaxis, wherein the flap protruding holes 93 are arranged opposite to eachother. Each longer side 39 a forming the periphery of each of the flapprotruding holes 93 is formed with flap opening prevention taps 95, 95substantially at the central areas thereof in such a manner that theflap opening prevention taps 95, 95 protrude toward one another in thecircumferential direction of the cylindrical section 87.

As illustrated in FIG. 9A, the inner face of the constricted spot 89 ofthe outer fastening ring 29 is formed in a substantially oval shape, sothat the diameter of the major axis DL and the diameter of minor axis DSare formed in different sizes. Line C-C in FIG. 9A is a line thatinterconnects the centers of the widths of the flap protruding holes 93,93 in the circumferential direction, wherein line C-C indicates acentral position in the circumferential direction where the flapprotruding holes 93, 93 are formed. The line C-C has a slope of apredetermined angle (for example, about 45°), and the flap protrudingholes 93, 93 are formed to correspond the phase angle of the connectiontail section 43 of the clip body 27.

As illustrated in FIG. 10, an inner diameter step part 97 is formed overthe entire circumference of the boundary of the inner peripheries of thecylindrical section 87 and the constricted spot 89. Between thecylindrical section 87 and the constricted spot 89, a pair of planarparts 79 are formed at circumferential positions substantially the samewith the flap protruding holes 93, wherein the planar parts 79 graduallyreduce the diameter from the outer diameter of the cylindrical section87 to an outer diameter in the vicinity of the outer diameter of theconstricted spot 89 along the axis.

For this reason, the diametrical cross-sectional shape of the area ofthe planar part 79 between the cylindrical section 87 and theconstricted spot 89 has parallel parts formed by the planar parts 79 andcircular arc parts formed by the cylindrical section 87. Thisdiametrical cross-sectional shape is similar to the diametricalcross-sectional shape of the ring part 77 (see FIG. 6) of the innerfastening ring 31, and the inner diameter of the outer fastening ring 29is slightly larger than the outer diameter of the ring part 77 of theinner fastening ring 31.

FIG. 11 is a cross-sectional view illustrating the outer fastening ring29 and the inner fastening ring 31 in a state where they are engagedwith each other.

The outer fastening ring 29 and the inner fastening ring 31 are engagedwith each other by inserting the inner fastening ring 31 into thecylindrical section 87 of the outer fastening ring 29 in such a mannerthat the ring part 77 side is positioned at the forefront. The innerfastening ring 31 is positioned in the axial direction as the front endface 77 b of the ring part 77 abuts against the inner diameter step part97 of the constricted spot 89. In addition, the position of the innerfastening ring 31 in the rotating direction is determined by fitting theplanar parts 77 c of the ring part 77 of the inner fastening ring 31 inthe inner periphery of the parts formed with the planar parts 79 in theouter fastening ring 29, and fitting the ring part 77 of the innerfastening ring 31 in the outer fastening ring 29.

In addition, the flap opening prevention taps 95 of the outer fasteningring 29 are respectively inserted into the flap locking holes 85provided in the pair of flap parts 45 of the inner fastening ring 31,and the flap opening prevention taps 95 respectively abut against oneside 85 a of the flap locking holes 85. As a result, the flap parts 45configured to be expanded by elastic resilience are prevented from beingexcessively opened by abutting against the flap opening prevention taps95, and the expansion angle of the flap parts 45 can be securelymaintained at a predetermined angle established at the time of design.

In addition, since the maximum outer diameter of the loop parts 47 ofthe clip body 27 is determined in a size that makes the loop parts 47abut against the taper section 91 of the outer fastening ring 29, theinner fastening ring 31 and the clip body 27, which are formedintegrally with each other, are prevented from being deviated to therear side in relation to the outer fastening ring 29. Furthermore, theclip body 27 is inseparably engaged with the inner fastening ring 31.For this reason, the clip body 27 and the outer fastening ring 29 willnot be deviated from each other by vibration at the time oftransportation or the like.

<Handle Manipulation Unit>

FIG. 12 is a cross-sectional view of the handle manipulation unit of theligation device.

As described above, the handle manipulation unit 17 includes amanipulation unit body 33 to which the base end side of the base endsheath 19 is fixed to be rotatable around the axis, a slider 35, and afinger pull ring 37. The manipulation unit body 33 is provided with aslitting section 99 formed with a slit along the axial direction, andthe slider 35 is configured to be movable in the axial direction withinthe slit forming extension. The slider 35 consists of a slider body 115and a manipulation wire anchor 113.

FIG. 13 is an enlarged cross-sectional view of the front end part A1 ofthe manipulation unit body 33 and a part A2 in the vicinity of the frontend part of the slitting section 99 illustrated in FIG. 12.

A fixing clasp 107 is provided at the front end of the manipulation unitbody 33, wherein a base end sheath 19 with the manipulation wire 21inserted therein, and an bending prevention spring 111 configured tocover and protect the base end sheath 19 are inserted into the front endpart 107 a of the fixing clasp 107 along the axis. On the front end ofthe manipulation unit body 33, a cap 109 is press-fitted.

The manipulation wire 21, which extends out from the base end sheath 19,extends to the slider 35 from the base end of the fixing clasp 107. Themanipulation wire 21 is inserted which is covered by the bucklingprevention pipe 117 through the guide pipe 105 arranged in the base endside of the fixing clasp 107. The guide pipe 105 extends to an area inthe vicinity of the front end part of the slitting section 99 toslidably accommodate the buckling prevention pipe 117. In addition, thebuckling prevention pipe 117 extends to the slider 35 to retain themanipulation wire 21 in the linear shape.

The front end of the buckling prevention pipe 117 is slidably fitted inthe guide pipe 105, and when the slider 35 is slid, specifically, whenthe slider 35 is moved in the direction opposite to the finger pull ring37, the buckling prevention pipe 117 prevents the occurrence of bucklingof the manipulation wire 21, thereby enabling the stable manipulation ofthe manipulation wire 21.

In the base end side of the guide pipe 105, there are provided an O-ring103 and a washer 101. The washer 101 is locked by a stepped part 33 a ofthe manipulation unit body 33 to restrain the axial movement of theO-ring 103. The inner diameter of the washer 101 is smaller than theouter diameter of the O-ring 103 to prevent the O-ring 103 from escapingto the rear side. In addition, a gap is provided between the washer 101and the guide pipe 105, and a gap is also provided between the O-ring103 and the guide pipe 105.

The buckling prevention pipe 117 is inserted through the guide pipe 105,the O-ring 103 and the washer 101 with a proper gap for enabling therotation of the buckling prevention pipe 117. The inner diameter of theguide pipe 105 is determined as a size that enables the insertion of thebuckling prevention pipe 117, and provides a little clearance for themanipulation wire 21. The guide pipe 105 and the fixing clasp 107 areconfigured to be rotatable in relation to each other. The inner diameterof the O-ring 103 and the outer diameter of the buckling prevention pipe117 have a relationship in size such that they are rotatable around theaxis, and frictional resistance is produced in the axial direction. Theparts depicted by dotted lines in FIG. 13 indicate welded parts.

FIG. 14 is an exploded perspective view of a manipulation wire anchorfor anchoring the manipulation wire 21 to the slider 35, and FIG. 15 isa sectioned perspective view of the slider body.

The slider 35 is comprised of a slider body 115 and a manipulation wireanchor 113 configured in a halved structure. The slider 35 is fabricatedby combining the manipulation wire anchor 113 with the slider body 115fitted in the manipulation unit body 33 across the slitting section 99(see FIG. 12) and press-fitting and fixing the manipulation wire anchor113 to the slider body 115. The slider body 115 and the manipulationwire anchor 113 combined thereby become slidable along the slittingsection 99.

As illustrated in FIG. 14, the manipulation wire anchor 113 consists ofa top wire anchor 113 a and a bottom wire anchor 113 b, each of which issubstantially semi-circular. The top wire anchor 113 a and the bottomwire anchor 113 b have the same shape obtained by halving themanipulation wire anchor 113. Both the anchors 113 a and 113 b have arecess 121 for accommodating a caulking clasp 119 (illustrated in thedrawing as a flat shape after mashed) fixedly attached to the rear endof the buckling prevention pipe 117. The top wire anchor 113 a and thebottom wire anchor 113 b are combined with each other with depressions123 and protrusions 125. In addition, the bottom wire anchor 113 b has apair of recesses 127, 127 which are engaged with a pair of latchingclaws 129, 129 of the slider body 115 illustrated in FIG. 15 to preventrelative rotation thereof as well as to conduct positional alignmentthereof.

The buckling prevention pipe, the wire and the caulking clasp areintegrated with each other by fitting the buckling prevention pipe 117over the wire, fitting the caulking clasp 119 over the bucklingprevention pipe 117, and then caulking the caulking clasp with apressing tool or the like. The caulking clasp 119 is turned to anon-circular shape through the caulking process, and its relativerotation in relation to the manipulation wire anchor 113 is blocked. Asa result, the buckling prevention pipe 117 is fixed to the manipulationwire anchor 113 together with the manipulation wire 21 inserted throughthe buckling prevention pipe 117.

When performing manipulation by the handle manipulation unit 17configured as described above, a thumb is inserted into the finger pullring 37, and the index finger and the middle finger of the same hand arepositioned to grasp the slider 35 therebetween. In addition, in order torotate the clip unit around the axis, the manipulation unit body 33 isrotated.

The rotation of the manipulation unit body 33 is transmitted to theslider 35 and the manipulation wire 21 from the manipulation unit body33, as illustrated in FIG. 13. In addition, since the manipulation unitbody 33 and the fixing clasp 107 are rotatably fixed, the rotation ofthe manipulation unit body 33 is not transmitted to the sheaths 19, 15including the fixing clasp 107. That is, by rotating the manipulationunit body 33, the manipulation wire 21 is rotated but the base endsheath 19 and the front end sheath 15 are not rotated.

<Front End Sheath>

FIG. 16 is across-sectional view of the front end sheath. At the baseend of the front end sheath 15, the front end part of the base endsheath 19 is welded via a connection ring 131. The inner diameter of thefront end sheath 15 is slightly larger than the outer diameter of theouter fastening ring 29 (see FIG. 9), so that the outer fastening ring29 can be accommodated in the front end sheath 15. The manipulation wire21 extending from the base end sheath 19 is inserted through the frontend sheath 15, and protrudes to the outside toward the front side fromthe front end sheath 15. At the front end part which is the distal endof the manipulation wire 21, a hook 23 and a guide bead 25 are fixedthrough soldering or laser welding. As a result, when the slider 35 (seeFIG. 2) is slid in the axial direction in relation to the manipulationunit body 33, reciprocating actions are performed following the slideaction so as to push the manipulation wire 21 out of the front endsheath 15 to the front side and to return the manipulation wire 21 tothe front end sheath 15.

In addition, in the inside of the front end sheath 15 or the base endsheath 19, a retainer coil (a retainer member) 201 is arranged betweenthe front end sheath 15 or the base end sheath 19 and the manipulationwire 21. The retainer coil is formed of a highly wear-resistant hardmetal, such as a stainless steel, and is formed in a circularcross-section. By interposing the retainer coil 201 between the innerperiphery of the front end sheath 15 or the base end sheath 19 and themanipulation wire 21, the front end sheath 15 or the base end sheath 19and the manipulation wire 21 do not directly contact with each other andcontact with the retainer coil 201 with a small contact area.

For this reason, resistance against the reciprocation of themanipulation wire 21 in the front end sheath 15 or the base end sheath19 and resistance against the rotation of the manipulation wire 21 maybe reduced, and the manipulation wire 21 may be manipulated moresmoothly with excellent responsiveness. By determining the hardness ofthe retainer coil 201 to be substantially equal to that of themanipulation wire 21, the abrasion caused by the sliding movementbetween the retainer coil 201 and the manipulation wire 21 may besuppressed.

The front end part of the retainer coil 201 is fixedly attached to theguide bead 25, and the retainer coil 201 extends to the handlemanipulation unit side. As the retainer coil 201 is arranged in thefront end side of the front end sheath where the clip unit is mounted,it is possible to reduce contact resistance in relation to the front endpart of the front end sheath which has a lot of opportunities to becurved. For this reason, even if the front end sheath 15 iscomplicatedly curved, the reciprocation in the axial direction androtation of the manipulation wire 21 can be smoothly performed. Inaddition, by fixedly attaching the retainer coil 201 to the guide bead25, the arranging place of the retainer coil 201 will not be deviatedfrom the front end of the manipulation wire 21.

In addition, the rear end part of the retainer coil 201 is formed as afree end that is not fixed to the front end sheath 15 and themanipulation wire 21. Due to this, the retainer coil 201 becomesextensible within the front end sheath 15, and the rotation of the freeend is not restrained. Accordingly, a following performance, such as acurving behavior, can be enhanced.

It is more desirable for the retainer coil 201 to be in a loosely woundcondition in which adjacent coil parts are spaced from each other ratherthan in a closely wound condition in which adjacent coils contact witheach other. By forming the retainer coil 201 in the loosely woundedcondition, it is possible to further reduce the contact area, therebyfurther reducing contact resistance. In addition, when cleaning theinside of a sheath, the circulation of cleaning liquid may befacilitated, and the cleaning performance may be improved.

The winding direction of the retainer coil 201 is preferably in areverse direction to the winding direction for the densely wound coilsof the front end sheath 15 and the base end sheath 19. In addition, thewinding direction of the retainer coil 201 is preferably in a reversedirection to the winding direction of the stranded wire of themanipulation wire 21. In such a case, it is possible to prevent theretainer coil 201 from penetrating into gaps between strands in theinner surface of a sheath member or gaps between strands of themanipulation wire 21 to increase manipulation resistance. As a result,the twisting characteristics of the retainer coil 201 and themanipulation wire 21 may be averaged to remove unevenness in curvingcharacteristic.

<Hook>

FIG. 17 is a front view of the hook 23 and the guide bead 25 fixed tothe front end of the manipulation wire 21, and FIG. 18 is across-sectional view taken along line D-D of FIG. 17.

The hook 23 fixed to the front end of the manipulation wire 21 throughsoldering or laser welding is configured to have the maximum outerdiameter smaller than the inner diameter of the outer fastening ring 29(see FIG. 9) to be capable of being inserted into the outer fasteningring 29. The hook 23 has, from the front end thereof, a hook part 135,an under-head expanded-diameter part (expanded-diameter part) 137, and arear end expanded-diameter part 139, which are integrally formed. Thehook part 135 has a front end taper part (front side inclined surface)141 and an under-head taper part (rear side inclined surface) 143 formedin this order from the front end to the rear side of the hook 23. Thesectional area of the front end taper part 141 perpendicular to the axisLo of the hook 23 (See, FIG. 44) is gradually increased from the frontend to the rear side of the hook 23. And, the sectional area of the rearside inclined surface perpendicular to the axis Lo of the hook 23 (See,FIG. 44) is gradually reduced from the front end to the rear side of thehook 23. The inclined angle of the under-head taper part 143 is designedas an angle of for example, 90 degrees to 135 degrees in relation to theaxial direction, and deforms the J-shaped claw parts 73 of theconnection tail section 43, which is engaged with the under-head taperpart 143, to control the magnitude of force when releasing theengagement. The cross-section of the hook 23 is not limited to thecircular shape and may have a different shape, such as a pyramid shapeor the like.

The under-head expanded-diameter part 137 has front and rear sides, eachof which is formed in a taper shape, and a key recess 145 engaged withthe J-shaped claw parts 73 provided in the connection tail section 43 ofthe clip body 27 (see FIG. 4) is formed at a portion of the outerperiphery of the under-head expanded-diameter part 137. When the hook 23and the connection tail section 43 of the clip body 27 are connected,the under-head expanded-diameter part 137 maintains the coaxialitybetween the hook 23 and the connection tail section 43, and secures thestability of engagement. In addition, the rear end expanded-diameterpart 139 includes a small diameter part 147, and a large diameter part149 formed at the rear end of the small diameter part 147.

<Guide Bead>

The guide bead 25 is spaced from the hook 23 in the rear side of thehook 23 and fixed to the manipulation wire 21 by soldering or laserwelding. Since the hook 23 and the guide bead 25 are spaced from eachother and fixed to the manipulation wire 21, the manipulation wire 21may be curved therebetween and the degree of freedom in mutual movementmay be improved. At the front end of the guide bead 25, a front endtaper part 151 is formed, and at the rear end, a rear end taper part 153is formed. The front end taper part 151 has an effect of guiding theguide bead 25 into the outer fastening ring 29 to be smoothly insertedinto the outer fastening ring 29. The rear end taper part 153 has aneffect of guiding the guide bead 25 to the front end sheath 15 to besmoothly accommodated in the front end sheath 15 when the clip unit 13is pulled into the front end sheath 15.

The rear end taper part 153 is set to have a length that is exposed tothe rear side from the rear end of the outer fastening ring 29 when thehook 23 and the clip unit 13 are connected. Due to this, the rear endtaper part 153 can be smoothly introduced into the front end sheath 15without causing the front end part of the front end sheath and the rearend part of the clip unit 13 to be interfered with each other even ifthe entirety of the clip unit 13 has completely protruded to the outsidefrom the front end sheath.

FIG. 19 is a perspective view illustrating, partially in cut-away, theclip body and the hook in the state where they are engaged with eachother.

When the hook 23 and the clip unit 13 are connected, the clip body 27 isrestrained in rotating position around the axial direction since theJ-shaped claw parts 73 of the connection tail section 43 are engaged inthe key recess 145. In addition, the front ends 73 a of the J-shapedclaw parts 73 are engaged with the under-head taper part 143, therebydetermining the axial position of the clip body 27. In this state, sincethe key recess 145 is engaged with the connection tail section 43(J-shaped claw parts 73) of the clip body 27, the torque of themanipulation wire 21 can be transmitted to the clip body 27.

<Clip Case>

In the clip manipulation device 11 configured as described above, theclip unit 13 is mounted on the hook 23 provided at the front end of themanipulation wire 21, and a biological tissue is ligated by a pair ofthe arm parts of the clip unit 13. The clip unit 13 is accommodated in aclip case 161 in advance, which is illustrated in FIG. 20 as aperspective view, and the clip unit 13 is mounted on the hook 23 byinserting the hook 23 at the front end of the manipulation wire 21 intothe case from the accommodated state.

An exploded perspective view of the clip case is illustrated in FIG. 21.The clip case 161 is comprised of a top case 163 and a bottom case 165,and is configured by combining the top case 163 and the bottom case 165.The clip unit 13 is located in a clip receiving chamber 167 formedbetween the top case 163 and the bottom case 165. The top case 163 andthe bottom case 165 are integrated by engaging a plurality of engagementclaws 171 formed in the top case 163 with claw engagement parts 173formed in the bottom case 165.

A side view of the clip case is illustrated in FIG. 22. The top case 163has a sheath press part 169 narrowly formed in the thickness direction.In addition, an anti-slipping uneven pattern 175 is formed on the bottomcase 165 at a position corresponding to the sheath press part 169,thereby enhancing a grip performance when the clip case 161 is grasped.

<Mounting of Clip Unit>

A sequence of mounting the clip unit of the clip case to the hook isillustrated in FIGS. 23A to 23D. As illustrated in FIG. 23A, the clipunit 13 is arranged in the clip receiving chamber 167 in advance.

In order to mount the clip unit 13 to the clip mounting device, thefront end sheath 15 is firstly inserted into a sheath insertion part 179from a sheath guide part 177 of the clip case 161, which are illustratedin FIG. 20. In addition, the front end sheath 15 is pushed into thesheath insertion part 179 until the front end of the front end sheath 15is abutted against the end of the inside of the sheath insertion part179. In this state, the clip case 161 is gripped in the thicknessdirection while pressing the front end sheath 15 against the clip case161 as illustrated in FIG. 22.

The part indicated by arrow A3 of the bottom case 165 in FIG. 23A isillustrated in FIG. 24 as an enlarged view and is illustrated in FIG. 25as a perspective view, respectively.

As illustrated in FIGS. 24 and 25, the front end of the front end sheath15 is pushed into the sheath insertion part 179 to a position where thefront end abuts against the sheath abutting part 180. Then, the outerfastening ring 29 is positioned such that the taper section 91 of thefront end abuts against a fastening ring abutting part 183 in a statewhere the outer fastening ring 29 is laid in a fastening ring retainingpart 181 of a concavely curved shape. As a result, the clip unit 13 isprevented from getting out in the direction indicated by arrow Q in FIG.24. That is, even if a forward pushing force is applied to the clip unit13 by inserting the hook, the relative position of the clip unit 13 andthe clip case 161 is not changed. For this reason, the clip unit 13 isprevented from coming into contact with and being damaged by the clipcase 161.

Since the outer periphery of the outer fastening ring 29 is retained inthe fastening ring retaining part 181 corresponding to the outerperiphery, the outer fastening ring 29 is precisely retained within theclip case 161, and the outer fastening ring 29 may be arranged withoutaxial deviation. Therefore, the front end part of the front end sheath15 and the rear end part of the outer fastening ring 29 will notinterfere with each other when the front end sheath 15 is inserted intothe clip case 161.

In addition, the flap parts 45 of the inner fastening ring 31 come intocontact with the flap guide taper part 185 such that the clip unit 13laid in the clip case 161 is biased to the base end side not to bedisengaged. As a result, the clip unit 13 will not escape from the clipcase 161 by the self-weight of the clip unit 13, vibration at the timeof transportation, and handling of the clip case.

Then, the slider 35 of the handle manipulation unit 17 is moved forward,and the manipulation wire 21 is extended, so that the hook protrudes tothe outside from the front end of the front end sheath 15. FIGS. 26A to26C are explanatory views illustrating the hook from the state where itis inserted into the connection tail section 43 of the clip body 27 tothe state where it is connected to the connection tail section 43 in astep-by-step manner. The hook 23 starts to be engaged with theconnection tail section 43 as illustrated in FIG. 26A, then the J-shapedclaw parts 73 are moved to pass the under-head expanded-diameter part137 of the hook 23 as illustrated in FIG. 26B, and then the front ends73 a of the J-shaped claw parts 73 are engaged with the under-head taperpart 143 of the hook 23 as illustrated in FIG. 26C, thereby completingthe connection between the hook 23 and the clip body 27.

Next, the slider 35 of the handle manipulation unit 17 is moved backwardto pull the manipulation wire 21 backward. As such, as illustrated inFIG. 23B, the flap parts 45 extending radially outward from the outerfastening ring 29 are closed. FIG. 27 is an enlarged explanatory viewillustrating the flap parts while they are being closed. When themanipulation wire 21 is pulled backward, the front ends 73 a of theJ-shaped claw parts 73 are abutted against the under-head taper part 143of the hook part 135, whereby the pulling force is transmitted to theclip unit 13. When the clip unit 13 is pulled out to the base end sidein relation to the clip case 161, the free ends 45 a of the flap parts45 abut against the flap guide taper part 185 of the clip case 161,thereby gradually reducing the opening extent, and finally closing theopening to the extent of the outer diameter of the outer fastening ring29.

When the free ends 45 a of the flap parts 45 are closed to the outerdiameter of the outer fastening ring 29, the clip unit 13 is insertedinto the front end sheath 15 as illustrated in FIG. 23C. The force atthe time of closing the flap parts 45 is set to be sufficiently smallerthan that for deforming and introducing the loop parts 47 of the baseend section 41 (see FIG. 4) of the clip body 27 into the outer fasteningring 29. For this reason, the flap parts 45 are securely closed.

In addition, when the flap parts 45 are closed, hook abutments 187 ofthe flap parts 45 abut against a flap abutting taper part 189 of thehook 23. Due to this abutting of the hook abutments 187, the relativemovement between the hook 23 and the inner fastening ring 31 isrestrained, and the reciprocating movement by the manipulation wire 21in the axial direction may be directly transmitted to the innerfastening ring 31. That is, the position for transmitting force from thehook 23 to the clip unit 13 after the flap parts 45 are closed ischanged from the engagement position of the J-shaped claw parts 73 andthe under-head taper part 143 of the hook 23 to the engagement positionof the hook abutments 187 and the flap abutting taper part 189 of thehook 23.

When the manipulation wire 21 is pulled backward, the clip unit 13 isstored in the front end sheath 15 as illustrated in FIG. 23D. When theclip unit 13 is stored, the arm parts 39 of the clip body 27 are guidedto the ring part 77 of the inner fastening ring 31 (see FIG. 6) andinserted into the front end sheath 15 while being closed.

As such, the clip unit 13 is mounted to the clip manipulation device 11illustrated in FIG. 1.

<Manipulation for Ligation>

Next, manipulation for ligating a biological tissue by the ligationdevice 100 illustrated in FIG. 1 will be described.

(Insertion of Sheath into Forceps Channel)

An operator of an endoscope inserts the front end sheath 15 into aforceps channel which is a treatment instrument insertion passage of theendoscope in a state where the clip unit 13 is stored in the front endsheath 15 of the ligation device 100. In such a case, the connected formof the clip body 27 and the outer fastening ring 29 is changed to acurved state illustrated in FIG. 28B by following the curve of the frontend sheath 15 from the linear state illustrated in FIG. 28A. Since thehook 23 and the guide bead 25 are spaced from each other and fixed tothe manipulation wire 21, the manipulation wire 21 can be curved betweenthe hook 23 and the guide bead 25, and the degree of freedom in mutualmovement can be enhanced.

The outer fastening ring 29 is formed from a hard metal material. Forthis reason, the longitudinal length of the outer fastening ring 29determines the facilitation of insertion in relation to the endoscope,and it is desirable that the entire length of the outer fastening ring29 is short.

As illustrated in FIG. 29, the guide bead 25 may be replaced by a guidespring 191 arranged to the outside of the manipulation wire 21 in therear side of the outer fastening ring 29. By setting the guide spring191 is a length that makes the rear end of the guide spring 191 bealways inserted into the front end sheath 15 in the entire stroke areaof the reciprocating movement of the manipulation wire 21 in the axialdirection, it is possible to secure the following performance forcurving and a guidance performance to the front end sheath 15.

As illustrated in FIG. 30, a guide bead 25A having a rear end taper part25 a may be provided at the rear end of the guide spring 191A. The guidebead 25A is fixed to the manipulation wire 21 by soldering or welding.The guide spring 191A is arranged to be free between the hook 23 and theguide bead 25A without being biased. With this arrangement, even if theguide spring 191A is set in a length that makes the rear end thereofproject from the front end sheath 15, the rear end of the guide spring191A can be introduced into the front end sheath 15 without interferencebetween the front end 15 a of the front end sheath 15 and the guidespring 191A. Accordingly, the following performance for curving and theguidance performance to the front end sheath 15 can be secured and theentire length of the guide spring 191A can be set shortly. Therefore,the flexibility can be further enhanced.

(Clip Protrusion from Front end sheath)

FIGS. 31A to 31F illustrate the arm parts of the clip unit until theyare expanded from the front end sheath.

As illustrated in FIG. 31A, the clip unit 13 protrudes to the outsidefrom the front end of the front end sheath 15 by continuously feedingthe manipulation wire toward the front side by manipulation from thehandle manipulation unit in the state where the clip unit isaccommodated in the front end sheath 15. FIG. 31B illustrates the clipunit 13 when the arm parts 39 start to protrude from the front endsheath 15.

When the clip unit 13 protrudes to the outside from the front end sheath15, the arm parts 39 are gradually expanded as illustrated in FIG. 31C.Then, when the flap protruding holes 93 of the outer fastening ring 29completely get out of the front end sheath 15 as illustrated in FIG.31D, the flap parts 45 are elastically returned from the flap protrudingholes 93 and hence individually opened diametrically outward. The flapparts 45 are maintained at a predetermined opening angle where each ofthe flap opening prevention taps 95 is engaged with one side 85 a ofeach one of the flap locking holes 85 (see FIG. 11).

Then, as illustrated in FIG. 31E, the clip unit 13 further protrudesfrom the front end sheath until the flap parts 45 are certainly opened,and as illustrated in FIG. 31F, the clip unit 13 is returned to the rearside by pulling the manipulation wire to the base end side. At thistime, the free ends 45 a of the flap parts 45 are stopped at a positionwhere they abut against the front end 15 a of the front end sheath 15.

That is, the flap parts 45 function as a stopper for defining the axialpositions of the clip unit 13 and the front end sheath 15. Thediametrically outward opening angle of the flap parts 45 is determinedby the designed sizes of the outer fastening ring 29 and the innerfastening ring 31 and is constant since it is not varied depending onthe front end sheath 15. For that reason, even if the clip unit 13 andthe front end sheath 15 are deviated or inclined in relation to theaxis, the free ends 45 a of the flap parts 45 certainly abut against thefront end 15 a of the front end sheath 15 to function as a stopper at acorrect position since the flap parts 45 are opened with high precisionat the designed opening angle. Accordingly, it is possible to alwayscorrectly position the clip unit 13 in relation to the front end sheath15 to axially coincide with the front end sheath 15, and the subsequentligation action can be smoothly and reliably performed.

(Opening/closing Action of Arm Parts)

Next, the opening/closing action of the arm parts for gripping abiological tissue will be described.

FIGS. 32A to 32E illustrate the actions of the arm parts of the clipunit, from expanding after having protruded to the outside from thefront end sheath to ligating a biological tissue, in a step-by-stepmanner.

Since the arm parts 39 of the clip body 27 are closed when the clip unit13 stored in the front end sheath 15, the clip unit 13 tends to beclosed, thereby reducing the opening angle. The plastic deformation ofthe base end section 41 may compensate for the reduction of the openingangle.

When the base end section 41 of the clip body 27 illustrated in FIG. 32Ais inserted into the constricted spot 89 of the outer fastening ring 29by being pulled by the manipulation wire, the loop parts 47, 47 aregradually narrowed as illustrated in FIG. 32B, and hence the base endsection 41 is plastically deformed. That is, the outer diameter of thebase end section 41 of the clip body 27 is larger than the innerdiameter DS (see FIG. 9) in the major axis side in the constricted spot89 of the outer fastening ring 29. For this reason, when the base endsection 41 of the clip body 27 is pulled into the outer fastening ring29, the loop parts 47, 47 of the base end section 41 are pressed anddeformed from the opposite sides thereof.

As the loop parts 47, 47 of the base end section 41 are deformed, thearm parts 39, 39 of the clip body 27 perform expansion movement using adeviation prevention claw 51 as a fulcrum point. Accordingly, asillustrated in FIG. 32B, the arm parts 39, 39 are widely expanded asillustrated to have an opening size that is capable of gripping asufficient amount of tissue.

The timing of expanding the arm parts 39, 39 is transmitted to anoperator as timing when a resistance against the pulling of themanipulation wire has occurred. That is, an expansion retainingprotrusion 55 of the inner fastening ring 31 illustrated in FIG. 33A isintroduced into the slit part 53 formed in the base end section 41 ofthe clip body 27 as the base end section 41 is moved to the base endside (downward in the drawing) by pulling the manipulation wire. Whenthe manipulation wire is pulled again, the expansion retainingprotrusion 55 abuts against the front end part 55 a of the slit part 53,thereby producing a resistance against the pulling of the manipulationwire as illustrated in FIG. 33B.

With the resistance, the operator may readily recognize that the armparts 39, 39 are opened at their maximum, and may temporarily stop thepulling operation of the manipulation wire in the state where the armparts 39, 39 are opened at their maximum.

(Rotation of Clip)

As illustrated in FIG. 32C, the operator moves the clip unit 13 mountedin the front end sheath to a treatment position within a body cavity inthe state where the arm parts 39, 39 are kept expanded. Then, the clipunit 13 is rotated according to a treatment direction. As describedabove, the rotation of the clip unit is performed by rotating themanipulation unit body 33 illustrated in FIG. 34 around the axis

(Starting of Ligation)

Next, as illustrated in FIG. 32C, the operator sets the arm parts 39, 39to a target treatment position (an affected area 195), and pulls theslider 35 of the handle manipulation unit 17 (see FIG. 34) to the rearside, i.e., to the finger pull ring 37 side. Accordingly, as illustratedin FIG. 32D, the arm parts 39, 39 are closed, and the affected area 195is gripped. At this time, the bent linear plate parts 57 of the armparts 39, 39 (see FIG. 4) slidably contact with the inner diameter areasof the major axis (DL) side in the constricted spot 89 of the outerfastening ring 29 (see FIG. 9), and hence the ligation action of theclip is performed.

At this time, in the base end section 41 of the clip body 27 illustratedin FIG. 33, the expansion retaining protrusion 55 formed in the slitpart 53 is plastically deformed, so that the engagement between the clipbody 27 and the inner fastening ring 31 is released. The expansionretaining protrusion 55 is set to be plastically deformed by a force inthe extent of 10 N to 20 N, and the engagement with the inner fasteningring 31 may be readily released with the force applied when gripping theaffected area 195 with the arm parts 39, 39.

As a result, the clip body 27 is made to be movable backward again, andby retracting the slider 35 to the finger pull ring 37, the clip body 27is inserted into the outer fastening ring 29 as illustrated in FIG. 32E.

(Ligation State)

When the arm parts 39, 39 are completely closed, a disengagementprevention protrusion 59 formed widely on a portion of each of the armparts 39 is locked at the stepped part 89 a formed by the constrictedspot 89 of the outer fastening ring 29 as illustrated in FIG. 35. As aresult, it is possible to prevent the clip body 27 from coming out tothe front side of the outer fastening ring 29, and the ligation state bythe arm parts 39, 39 will be retained.

In addition, when the clip body 27 is moved backward (downward in thedrawing), the taper part 65 of the arm parts 39 and the pull-inprevention protrusions 61 abut against the inner diameter areas of theminor axis DS side of the constricted spot 89 (see FIG. 9), so that theclip body 27 cannot be further pulled into the outer fastening ring 29.

FIG. 36 illustrates a view shown in the direction indicated by arrow V2in FIG. 35.

As described above, the shape the inside of the constricted spot 89 isformed in an oval shape, in which the diameter of the major axis DL andthe diameter of the minor axis DS are different from each other. Themajor axis of the constricted spot 89 is set to coincide with theexpansion direction of the arm parts 39, 39 of the clip body 27. Due tothis, the constricted spot 89 abuts against the loop parts 47, 47 of thebase end section 41 (see FIG. 4) to control the expansion extent of thepair of arm parts 39. In addition, the minor axis of the constrictedspot 89 is set to be parallel to the widthwise direction of the each ofthe pull-in prevention protrusions 61 on the arm parts 39, 39. Due tothis, when the clip body 27 is accommodated in the outer fastening ring29, the constricted spot 89 engaged with the pull-in preventionprotrusions 61 to control the pull-in extent of the clip body 27.

(Release of Clip Unit)

FIG. 37 illustrates, partially, in cut-away, the clip unit in the statewhere the clip unit has completed ligation.

If the pulling force of the hook 23 is further increased in the statewhere the pull-in prevention protrusions 61 formed on the arm parts 39of the clip body 27 and the constricted spot 89 of the outer fasteningring 29 are engaged with each other, a tensile force is also applied tothe engagement part between the hook 23 and the connection tail section43 of the clip body 27.

FIG. 38A illustrates the hook and the connection tail section in theengaged state, and FIG. 38B illustrates the hook and the connection tailsection in the state of starting to release the engagement. Asillustrated in FIG. 38A, the hook part 135 of the hook 23 is positionedsuch that the front ends 73 a of the J-shaped claw parts 73 of theconnection tail section 43 abut against the under-head taper part 143formed on the rear side from the largest outer diameter area of thefront end taper part 141. When the hook 23 is returned backward inrelation to the connection tail section 43, the J-shaped claw parts 73are forcibly spread diametrically outward, thereby releasing theengagement with the under-head taper part 143 as illustrated in the FIG.38B.

FIGS. 39A to 39C illustrate a process of releasing the J-shaped clawparts from the engagement in a step-by-step manner.

As illustrated in FIG. 39A, when the hook 23 is returned backward fromthe state in which the front ends 73 a of the J-shaped claw parts 73 ofthe connection tail section 43 abut on the under-head taper part 143,the front ends 73 a of the J-shaped claw parts 73 are expandeddiametrically outward while being slid on the under-head taper part 143.In addition, when the front ends 73 a of the J-shaped claw parts 73 arespread diametrically outward over the maximum outer diameter of the hookpart 135 as illustrated in FIG. 39B, the hook 23 is disengaged from theconnection tail section 43 and the engagement of the hook 23 and theconnection tail section 43 is released as illustrated in FIG. 39C.

Due to this, it is possible to retract the clip manipulation devicewithin a body cavity in the state where the clip unit that has ligated abiological tissue such as an affected area is detained in the bodycavity.

<Examples of Other Configurations of Clip Body>

FIGS. 40A and 40B and FIGS. 41A and 41B illustrate different examples ofconfiguration of the connection tail section 43, respectively.

FIG. 40A is a partial configuration view of a connection tail sectionformed with a pair of engagement claw parts 73A, 73A, and FIG. 40B is abottom view of FIG. 40A. In this example of configuration, the pair ofthe engagement claw parts 73A, 73A are provided respectively to extendtoward the front side with reference to the rear end 71 a of the arm71A. The engagement claw parts 73A, 73A are inwardly inclined toward thecentral axis of the hook accommodated by the connection tail section 43Aas illustrated in FIG. 40B.

With this arrangement, the engagement claw parts 73A, 73A abut againstthe rear inclined surface of the hook, whereby the connection strengthbetween the clip unit and the hook can be increased. In addition, thenumber of the engagement claw parts is not limited two, and three ormore engagement claw parts may be provided

In addition, since the loads from the engagement claw parts 73A, 73A areuniformly applied and the bending moment applied to the part 71A isreduced, it is possible to increase the connection strength.

FIG. 41A illustrates a partial configuration view in which an engagementclaw part is arranged in an opening formed in an arm 71B, and FIG. 41Bis a bottom view of FIG. 41A. In this example of configuration, anopening 199 is formed in the vicinity of the rear end 71 a of the arm71B, and an engagement claw part 73B is provided in the opening 199 toextend from the rear end 71 a side of the opening 199 to the front side.The engagement claw part 73B is inclined inwardly toward the centralaxis of the hook to the same with the above-described claw parts.

With this arrangement, the engagement claw part 73B may be simplyconfigured. As a result, it is easy to fabricate and assemble.

The above-described clip body 27 may be formed by bending a flatmetallic plate, and a large force is applied to the arm parts 39, 39 atthe time of ligation. Therefore, as illustrated in FIG. 42, a clip body27A is formed with reinforcement ribs 197, 197 extending in thelongitudinal direction with the second bending points 64 b as thecenters, respectively, to increase the strength of the clip body 27A.The reinforcement ribs 197, 197 are formed to bulge on the inner sideswhich the pair of the arm parts 39, 39 are opposite to each other.

FIG. 43 is a cross-sectional view taken along line E-E of FIG. 42. Eachof the reinforcement ribs 197 is formed by pressing an arm part 39 inthe thickness direction of the plate. Since the strength of the clipbody 27 is increased by providing the reinforcement ribs 197, 197, astronger ligation may be performed for a biological tissue, and the armparts may be formed more narrowly to miniaturize the clip body.

<Other Example of Configuration of Flap Parts>

Next, another example of configuration will be described in which theflap parts of the clip unit 13 are expanded in the diametrically outwarddirection of the fastening ring 26 to abut against the front end of thefront end sheath 15, thereby positioning the clip unit 13 in relation tothe front end sheath 15.

FIG. 44 is a perspective view illustrating another example of the innerfastening ring. The parts common to those illustrated in FIGS. 6A to 6Cwill be denoted by the same reference numerals, and the descriptionthereof will be omitted or simplified. Like the configurationillustrated in FIGS. 6A to 6C, an inner fastening ring 31A includes apair of flap parts 45A, 45A, each of which is cantilevered on the ringpart 77 of the inner fastening ring 31A and extends along thelongitudinal axis of the inner fastening ring 31A. The free ends 45 a ofthe flap parts 45A are elastically biased in the diametrically outwarddirection of the inner fastening ring 31A.

An outer fastening ring combined with the inner fastening ring 31A onthe same axis has a configuration where the flap opening prevention taps95 are not provided at a pair of longer sides 93 a of the flapprotruding hole 93, which is the same with the outer fastening ring 29illustrated in FIGS. 9A and 9B.

Each of the flap parts 45A, 45A of the inner fastening ring 31A has acircular arc shape when it is viewed in a cross-section lying at rightangles to the longitudinal axis of the inner fastening ring 31A, inwhich the circular arc shape has a curvature smaller than that of theinner periphery of the outer fastening ring 29. With the circular arcshape, it is possible to secure a large inner space of the innerfastening ring 31A.

The free ends 45 a side of each of the flap parts 45A is formed withprojection parts 251, 251 protruding to the opposite sides from the sidesurfaces of the flap part 45A. The projection parts 251, 251 abutagainst the edges 29 a of the inner peripheries in the flap protrudingholes 93 of the outer fastening ring 29 illustrated in FIG. 45,respectively, whereby the expansion extent of the each of the flap parts45A, 45A is retained at a predetermined extent.

With this arrangement, the flap parts 45A, 45A retain the expansionextent thereof constant in the state where they protrude diametricallyoutward from the flap protruding holes 93. That is, a pair of theexpanding flap parts 45A, 45A can be prevented from being openedexcessively or insufficiently, and the expansion angle of the flap parts45A, 45A can be reliably retained at the angle set at the time ofdesign.

Although the example of configuration is provided with the flap parts45A on the inner fastening ring 31, 31A, the outer fastening ring 29 maybe provided with a flap part. In addition, it is possible to integrallyform the inner fastening ring and the outer fastening ring with the samemember, and to provide a flap part on the single integrally-formedfastening ring.

FIG. 46 is a perspective view schematically illustrating a constructionin which a single fastening ring is provided with a flap part.

On the single fastening ring 26A, a flap part 45B is cantilevered. Theflap part 45B is formed by cutting a part of the cylindrical fasteningring 26A. For that reason, an opening hole 255 is formed in a side ofthe fastening ring 26A. On the free end of the flap part 45B side, apair of projection parts 257 and 257 extend, which are configured toabut against the inner periphery of the fastening ring 26A.

The flap part 45B is elastically biased in the diametrically outwarddirection of the fastening ring 26A in advance. As a result, the flappart 45B can retain the expansion extent at a predetermined extent inthe state in which the projection parts 257, 257 abut against the innerperiphery of the fastening ring 26A.

In addition, as described above, by forming the flap part with a thinmetal plate, it is possible to reduce the thickness of the fasteningring itself, and to secure a large inner space. For this reason, theclip body and the hook may be directly connected within the fasteningring, no that it is not necessary to separately provide a connectionmember for connecting the clip body and the hook. Accordingly, it ispossible to omit an operator's work for removing the connection memberremaining in a ligation device whenever performing clipping, which maycontribute to the speedup of a surgical operation. In addition, even ifthe connection member is used in the configuration, it is possible tominiaturize the flap part itself. Consequently, a clipping adaptive toan endoscope having a treatment instrument insertion channel of asmaller diameter can be realized.

As described above, the ligation device 100 is not limited to using itas a ligation device but may be converted into another treatmentinstrument for an endoscope that has a hook and an engagement claw part.In addition, it is possible to configure an endoscope system whichenables a smooth endoscopic treatment by inserting the ligation device100 through a treatment instrument inserting channel, through which asheath member of an endoscope is inserted, and then introducing theligation device 100 to the inside of a body cavity.

Like this, the present invention is not limited to the above-describedexemplary embodiments. It is expected by the present invention thatmodifications and applications will be made by a person skilled in theart based on the disclosure of the specification and a well-knowntechnology, and the modifications and applications are included in thescope to be protected.

As described above, the following items are disclosed in thespecification.

(1) A clip unit for ligating a biological body includes: a clip bodyhaving a pair of arm parts; and a fastening ring arranged in an outsideof the clip body, and configured to fasten the arm parts, in which: thefastening ring includes a flap part configured to expand diametricallyoutward from the fastening ring, and a flap retaining unit configured toretaining an expansion extent of the flap part at a given extent.

With this clip unit, the expansion extent of the flap part is securelyretained at a predetermined extent by the flap retaining unit providedon the fastening ring. For this reason, the clip unit can always becorrectly positioned in relation to a sheath member to axially coincidewith the sheath member.

(2) In the clip unit according to ( ): the flap part is cantilevered onthe fastening ring to extend along a longitudinal axis of the fasteningring, and a free end of the flap part is elastically biased to adiametrically outside of the fastening ring, and the flap retaining unitengages with the flap part, to restrain the expansion extent of the flappart.

With this clip unit, since the expansion extent of the flap part iscontrolled by the engagement of the fastening ring and the flap part,the expansion extent can be defined with excellent precision.

(3) In the clip unit according to (2): the fastening ring is configuredby combining an inner fastening ring configured to support the flappart, and an outer fastening ring configured to cover the outside of theinner fastening ring and provided with a flap protruding hole, and theflap retaining unit retains the flap part in a state where the flap partprotrudes diametrically outward from the flap protruding hole.

With this clip unit, the flap part is configured to expand and protrudefrom the flap protruding hole in the state where the inner fasteningring and the outer fastening ring are combined.

(4) In the clip unit according to (3): the cross-section of the flappart perpendicular to a longitudinal axis of the inner fastening ring isformed in a circular arc shape having a curvature smaller than that ofan inner periphery of the outer fastening ring, and a flap locking holeis formed between a center of the circular arc and an end of thecircular arc of the flap part, and the flap retaining unit includes alocking claw protruding from the flap protruding hole of the outerfastening ring toward an inside of the hole, and when inserted into theflap locking hole, abutting against a side surface of the flap lockinghole.

With this clip unit, the expansion extent of the flap part is definedthrough the abutment of the side surface of the flap locking hole andthe locking claw.

(5) In the clip unit according to (4): plural pairs of flap lockingholes and locking claws which are engaged with each other.

With this clip unit, since the plural pairs of the flap locking holesand locking claws exist, it is possible to retain the flap part morestably.

(6) The clip unit according to (3) further includes: the flap partincludes a projection part formed at the free end side thereof, andabutting against an edge of the flap protruding hole of the outerfastening ring.

With this clip unit, the expansion extent of the flap part is definedthrough the abutment of the edge of the flap protruding hole of theouter fastening ring and the projection part.

(7) In the clip unit according to (6): the flap part includes pluralprojection parts. With this clip unit, the flap part is retained morestably due to the existence of the plural projection parts.

(8) In the clip unit according to any one of (1) to (7): the flap partis provided a plural areas on the fastening ring.

With this clip unit, the flap part is adapted to be expanded at theplural areas on the fastening ring. For this reason, it is possible toobtain an effect of either stabilizing the posture or distributingforce, for example when the flap parts abut against the front end of thesheath member, so that the clip unit can be stably supported.

(9) In the clip unit according to any one of (1) to (7): the flap partis installed to be capable of being embedded by being elasticallydeformed in an inside of the outer periphery of the fastening ring.

With this clip unit, the flap part may be embedded in the inside of thefastening ring. For this reason, the flap part does not interfere withthe sheath member when the clip unit is accommodated in the sheathmember.

(10) A ligation device includes: the clip unit according to any one of(1) to (9); a flexible elongated sheath member; a transmission memberinserted into the sheath member to be capable of being reciprocated, andconfigured to transmit driving force to the clip unit connected to thefront end of the transmission member; and a manipulation unit arrangedon a base end side of the sheath member opposite to the clip unit, andconfigured to transmit the driving force to the transmission member.

With this ligation device, it is possible to obtain an effect of eitherstabilizing the posture or distributing force, for example when the flapparts abut against the front end of the sheath member, so that the clipunit can be stably supported in the state in which the clip unit axiallycoincide with the sheath member at the front end of the sheath member.Accordingly, a smooth and certain ligation action can be obtained.

(11) The ligation device according to (10): the expansion extent of theflap part is an expansion extent that makes the flap part abut against afront end of the sheath member when the transmission member is pulledinto the sheath member.

With this ligation device, the flap part surely abuts against the end ofthe sheath member, thereby being positioned.

What is claimed is:
 1. A clip unit for lighting a biological bodycomprising: a clip body having a pair of arm parts; and a fastening ringarranged in an outside of the clip body, and configured to fasten thearm parts, wherein: the fastening ring includes a flap part configuredto expand diametrically outward from the fastening ring, and a flapretaining unit configured to retain the flap part, and the flapretaining unit engages with the flap part, to restrain the flap partfrom expanding diametrically outward from the fastening ring wherein theflap part is cantilevered on a ring part of the fastening ring to extendalong a longitudinal axis of the fastening ring, and the flap part iselastically biased diametrically outward from the fastening ring,wherein the fastening ring is configured by combining an inner fasteningring configured to support the flap part, and an outer fastening ringconfigured to cover the outside of the inner fastening ring and providedwith a flap protruding hold which is formed on a peripheral surface ofthe outer fastening ring and extends along the longitudinal axis of thefastening ring and the flap retaining unit retains the flap part in astate where the flap part protrudes diametrically outward from the flapprotruding hole.
 2. The clip unit according to claim 1, wherein: thecross-section of the flap part perpendicular to a longitudinal axis ofthe inner fastening ring is formed in a circular arc shape having acurvature smaller than that of an inner periphery of the outer fasteningring, and a flap locking hole is formed on the inner fastening ringbetween a center of the circular arc shape and an end of the circulararc of the flap part, and the flap retaining unit includes a lockingclaw protruding from the flap protruding hole of the outer fasteningring toward an inside of the hole, and when inserted into the flaplocking hole, abutting against a side surface of the flap locking hole.3. The clip unit according to claim 2, wherein: another flap lockinghole is formed in the flap part, and another locking claw engaging withsaid another flap locking hole is formed in the flap retaining unit. 4.The clip unit according to claim 1, further comprising: the flap partincludes a projection part formed at the free end side thereof, andabutting against an edge of the flap protruding hole of the outerfastening ring.
 5. The clip unit according to claim 4, wherein: the flappart includes plural projection parts.
 6. The clip unit according toclaim 1, wherein: another flap part is provided on the ring part of thefastening ring.
 7. The clip unit according to claim 1, wherein: the flappart is installed to be capable of being embedded by being elasticallydeformed in an inside of the outer periphery of the fastening ring.
 8. Aligation device comprising: the clip unit according to claim 7; aflexible elongated sheath member; a transmission member inserted intothe sheath member to be capable of being reciprocated, and configured totransmit driving force to the clip unit connected to the front end ofthe transmission member; and a manipulation unit arranged on a base endside of the sheath member opposite to the clip unit, and configured totransmit the driving force to the transmission member.
 9. The ligationdevice according to claim 8, wherein: the flap part is configured toabut against a front end of the sheath member when the transmissionmember is pulled into the sheath member.
 10. The clip unit according toclaim 1, wherein the flap part has a surface abutting against an innerperipheral surface of the fastening ring.
 11. The clip unit according toclaim 1, wherein the flap part comprises a thin plate.
 12. The clip unitaccording to claim 1, wherein the clip body is directly connected withinthe fastening ring.
 13. The clip unit according to claim 1, wherein theflap part comprises: a circular arc shape in a diametrical cross-sectionperpendicular to the axial direction; and a bulge part disposed at anaxially central area thereof, wherein a length of the circular arc shapein the diametrical cross-section is increased at the bulge part.
 14. Theclip unit according to claim 1, wherein the outer fastening ringincludes: a cylindrical section; a constricted spot formed by reducing adiameter of the cylindrical section in a vicinity of a front end of thecylindrical section; and a taper section extending from the constrictedspot such that a diameter of the taper section is increased towards afront end side.
 15. The clip unit according to claim 14, wherein theouter fastening ring and the inner fastening ring are engaged with eachother by inserting the inner fastening ring into the cylindrical sectionof the outer fastening ring in such a manner that a ring part side ispositioned at a forefront.